1. Field of the Invention
The present invention relates to a safety switch that ensures the bi-metallic plate to be deformed as desired when overloaded.
2. The Prior Arts
A conventional switch device, especially those switches using bi-metallic plate to prevent from being burned when an overloaded happens, generally includes a bi-metallic plate which is deformed when overloaded so as to separate the two contact points respectively located on the bi-metallic plate and one of the two terminals. Some inherent shortcomings for these conventional safety switches are found. There are too many parts involved in the safety switches and a longer period of time is required when assembling the switches, so this increases the cost of the products. The parts might be arranged inaccurately and this would affect the deformation of the bi-metallic plate. Once the bi-metallic plate is deformed to cut off the circuit, because of the improper arrangement of the parts as mentioned above, the bi-metallic plate could deform to re-connect the two contact points to connect the circuit again. Because of the inaccuracy of the deformation of the bi-metallic plate, the switch member does not set to the “OFF” position after the bi-metallic plate is deformed to cut off the circuit.
Therefore, it is desired to have a safety switch that allows the bi-metallic plate to deform toward a desired direction and has enough space for the deformation of the bi-metallic plate to prevent the bi-metallic plate from bouncing back to connect the circuit again.